1# SPDX-License-Identifier: GPL-2.0-only 2 3config HAVE_ARCH_KFENCE 4 bool 5 6menuconfig KFENCE 7 bool "KFENCE: low-overhead sampling-based memory safety error detector" 8 depends on HAVE_ARCH_KFENCE && (SLAB || SLUB) 9 select STACKTRACE 10 help 11 KFENCE is a low-overhead sampling-based detector of heap out-of-bounds 12 access, use-after-free, and invalid-free errors. KFENCE is designed 13 to have negligible cost to permit enabling it in production 14 environments. 15 16 See <file:Documentation/dev-tools/kfence.rst> for more details. 17 18 Note that, KFENCE is not a substitute for explicit testing with tools 19 such as KASAN. KFENCE can detect a subset of bugs that KASAN can 20 detect, albeit at very different performance profiles. If you can 21 afford to use KASAN, continue using KASAN, for example in test 22 environments. If your kernel targets production use, and cannot 23 enable KASAN due to its cost, consider using KFENCE. 24 25if KFENCE 26 27config KFENCE_STATIC_KEYS 28 bool "Use static keys to set up allocations" 29 default y 30 depends on JUMP_LABEL # To ensure performance, require jump labels 31 help 32 Use static keys (static branches) to set up KFENCE allocations. Using 33 static keys is normally recommended, because it avoids a dynamic 34 branch in the allocator's fast path. However, with very low sample 35 intervals, or on systems that do not support jump labels, a dynamic 36 branch may still be an acceptable performance trade-off. 37 38config KFENCE_SAMPLE_INTERVAL 39 int "Default sample interval in milliseconds" 40 default 100 41 help 42 The KFENCE sample interval determines the frequency with which heap 43 allocations will be guarded by KFENCE. May be overridden via boot 44 parameter "kfence.sample_interval". 45 46 Set this to 0 to disable KFENCE by default, in which case only 47 setting "kfence.sample_interval" to a non-zero value enables KFENCE. 48 49config KFENCE_NUM_OBJECTS 50 int "Number of guarded objects available" 51 range 1 65535 52 default 255 53 help 54 The number of guarded objects available. For each KFENCE object, 2 55 pages are required; with one containing the object and two adjacent 56 ones used as guard pages. 57 58config KFENCE_STRESS_TEST_FAULTS 59 int "Stress testing of fault handling and error reporting" if EXPERT 60 default 0 61 help 62 The inverse probability with which to randomly protect KFENCE object 63 pages, resulting in spurious use-after-frees. The main purpose of 64 this option is to stress test KFENCE with concurrent error reports 65 and allocations/frees. A value of 0 disables stress testing logic. 66 67 Only for KFENCE testing; set to 0 if you are not a KFENCE developer. 68 69config KFENCE_KUNIT_TEST 70 tristate "KFENCE integration test suite" if !KUNIT_ALL_TESTS 71 default KUNIT_ALL_TESTS 72 depends on TRACEPOINTS && KUNIT 73 help 74 Test suite for KFENCE, testing various error detection scenarios with 75 various allocation types, and checking that reports are correctly 76 output to console. 77 78 Say Y here if you want the test to be built into the kernel and run 79 during boot; say M if you want the test to build as a module; say N 80 if you are unsure. 81 82endif # KFENCE 83